Propionibacterium Acnes Pacemaker Implant Infections: an Under-recognized Cause

Introduction: Propionibacterium acnes (PA) is part of the normal microflora of human skin and is associated with cardiac implantable electronic devices (CIED) infections. This association is under-recognized and not well characterized.

Methods: Data of patients who underwent CIED extraction during 2015 was analyzed retrospectively. Baseline characteristics and clinical course were compared between patients who underwent extraction secondary to PA vs. Staphylococci aureus (SA) infections.

Results: in 2015, 32/46 (70%) underwent extraction due to infectious causes. Four of 32 (12.5%) extractions were secondary to PA infection while 11 (34.4%) were SA. Compared to SA infections, patients with PA were all male (vs. 72.7% of SA cases) of similar ages (62±20 vs.21±20; p=0.9). PA infection resulted in extraction in 14% (4/28) of males. Time from symptom onset to pathogen identification was longer for PA cases (50± 66.9 vs. 10±5.9 days in SA cases; p<0.05). Time to bacterial growth was 5-16 days (avg. 10 vs. 2 days for SA cases; p<0.01). The 4 PA cases were diagnosed by: systemic symptoms and positive blood cultures (BC) in 1, by pocket generator (PG) infection and lead vegetation with positive BC and sequencing of bacterial 16S ribosomal RNA genes from pus in another and by isolated PG inflammation in the other 2, for which pus cultures were positive and BC negative. Systemic infection presented 5-14 years after implantation while pocket infection emerged 1-9 days thereafter. All cases were treated with non 1st generation cephalosporin antibiotics and complete removal of the CIED system with full recovery.

Conclusions: Similar to SA, PA CIED infection cases both local and systemic infections. It is not uncommon in men, probably due to its residence in the skin`s pilosebaceous follicles. Diagnosis may be delayed due to slow growth. Therefore in susceptible patients prophylaxis with a non 1st generation cephalosporin should be considered.